linux-kernel - Re: [PATCH v2 1/3] media: i2c: imx219: Fix power sequence

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Message-ID: <CAPY8ntD38sM0SXvOEyr2gRCM7WeAY4CjAKcrVfd6MCHB+Ejv0A@mail.gmail.com>
Date:   Fri, 6 Mar 2020 13:01:39 +0000
From:   Dave Stevenson <dave.stevenson@...pberrypi.com>
To:     Lad Prabhakar <prabhakar.csengg@...il.com>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Linux Media Mailing List <linux-media@...r.kernel.org>,
        linux-kernel@...r.kernel.org,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: Re: [PATCH v2 1/3] media: i2c: imx219: Fix power sequence

Hi Prabhakar.

Thanks for the update.

On Fri, 6 Mar 2020 at 10:32, Lad Prabhakar <prabhakar.csengg@...il.com> wrote:
>
> When supporting Rpi Camera v2 Module on the RZ/G2E, found the driver had
> some issues with rcar mipi-csi driver. The sensor never entered into LP-11
> state.
>
> The powerup sequence in the datasheet[1] shows the sensor entering into
> LP-11 in streaming mode, so to fix this issue transitions are performed
> from "streaming -> standby" in the probe() after power up.
>
> With this commit the sensor is able to enter LP-11 mode during power up,
> as expected by some CSI-2 controllers.
>
> [1] https://publiclab.org/system/images/photos/000/023/294/original/
> RASPBERRY_PI_CAMERA_V2_DATASHEET_IMX219PQH5_7.0.0_Datasheet_XXX.PDF
>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>

Acked-by: Dave Stevenson <dave.stevenson@...pberrypi.com>


> ---
>  drivers/media/i2c/imx219.c | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
>
> diff --git a/drivers/media/i2c/imx219.c b/drivers/media/i2c/imx219.c
> index f1effb5a5f66..16010ca1781a 100644
> --- a/drivers/media/i2c/imx219.c
> +++ b/drivers/media/i2c/imx219.c
> @@ -1224,6 +1224,23 @@ static int imx219_probe(struct i2c_client *client)
>         /* Set default mode to max resolution */
>         imx219->mode = &supported_modes[0];
>
> +       /* sensor doesn't enter LP-11 state upon power up until and unless
> +        * streaming is started, so upon power up switch the modes to:
> +        * streaming -> standby
> +        */
> +       ret = imx219_write_reg(imx219, IMX219_REG_MODE_SELECT,
> +                              IMX219_REG_VALUE_08BIT, IMX219_MODE_STREAMING);
> +       if (ret < 0)
> +               goto error_power_off;
> +       usleep_range(100, 110);
> +
> +       /* put sensor back to standby mode */
> +       ret = imx219_write_reg(imx219, IMX219_REG_MODE_SELECT,
> +                              IMX219_REG_VALUE_08BIT, IMX219_MODE_STANDBY);
> +       if (ret < 0)
> +               goto error_power_off;
> +       usleep_range(100, 110);
> +
>         ret = imx219_init_controls(imx219);
>         if (ret)
>                 goto error_power_off;
> --
> 2.20.1
>